The construction of concrete culverts and other generally hollow, reinforced rectangular structures requires that a complicated array of forms and reinforcing bars must be constructed and aligned prior to the actual pouring of concrete. These forms are constructed one section at a time, typically every 12 feet or so, and are customized for each discrete section of culvert. Of course, this is very expensive and time consuming; and as the work in most instances is performed underground or below ground level, a danger exists that a side of an excavation in which the culvert is being constructed may collapse, burying or otherwise trapping workmen constructing the forms.
Accordingly, applicant has devised systems disclosed in U.S. Pat. No. 4,219,513, issued on Aug. 26, 1980, and No. 4,142,705, issued on Mar. 6, 1979. The '705 patent shows a method for constructing a culvert wherein reinforcing bars, known in the art as "rebar," are hung from timbers supported by hangers, in turn hung on frame members which form the outer walls of the culvert. Rebar for an inner support wall of the culvert is hung from timbers, in turn supported by transverse timbers also supported by the hangers, with all the rebar extending into the floor of the culvert when concrete for the floor is poured. After the floor sets, all the hangers and timbers are removed, leaving the outer forms and rebar for the vertical walls of the culvert in place. Next, wheeled, mobile, interior forms for forming interior vertical walls and the interior ceiling wall of the culvert are positioned between the rebar in the now-cured floor and the outer forms and elevated a short distance by removable blocks. Tubes for weep holes are fixed in the upper portion of the mobile form, along with rebar for the ceiling of the culvert, and concrete is then poured for the vertical walls and ceiling.
The '513 patent is a division of the '705 patent and discloses substantially the same material as the '705 patent.
In accordance with the foregoing, it is an object of this invention to provide a method and apparatus for constructing a concrete culvert which affords greater safety than prior methods.